Breaking Down the IP Code
An IP rating always consists of the letters "IP" followed by two digits. The first digit (0‑6) represents protection against solid foreign objects, ranging from large body parts down to fine dust. The second digit (0‑9K) indicates protection against water ingress, from vertical dripping to high‑pressure, high‑temperature jet sprays.
First digit – Solids protection
IP6X: Dust‑tight. No ingress of dust. This is the highest rating for solids and is the standard for any quality solar module's junction box and connectors.
Lower digits (1‑5) allow certain sizes of particles, but in solar applications, you almost always need IP6X because dust can cause electrical tracking, corrosion, or overheating.
Second digit – Liquids protection
This is where most variation occurs. Common ratings for solar components include:
IPX5: Water jets from any direction – no harmful effects.
IPX6: Powerful water jets (similar to heavy rain or hose washing).
IPX7: Temporary immersion up to 1 metre for 30 minutes.
IPX8: Continuous immersion under conditions specified by the manufacturer (often >1 metre).
IPX9K: High‑pressure, high‑temperature water jets – rarely needed for standard solar.
Typical solar junction boxes are referred to as being either "IP67" or "IP68" rated depending on if they are only temporarily submerged (IP67) or able to be long term submerged underwater (IP68). Solar connectors like MC4's also fall in this same range. Although the glass and encapsulant on the front of the solar module do not meet the definition of an enclosure and do not have an IP rating, the enclosure containing the electrical components do have an IP rating (to keep out dirt and water).
Why IP Ratings Matter in Solar Applications
Because solar modules are used outside for 25+ years it is exposed to extreme conditions such as sandstorms, monsoon rains, melting snow, salty mist (from the ocean), and industrial waste. If the junction box is not adequately sealed, moisture and dirt may enter into it, thus causing:
Corrosion of metal terminals and busbars will develop an increase in contact resistance and result in the development of hot spots.
Partial discharge or arcing inside connectors, a major fire risk.
PID (Potential Induced Degradation) accelerated by moisture ingress near the cell edges.
Ground faults that trip inverters and reduce system uptime.
This is the reason why trusted manufacturers utilize IP65, IP66, IP67, and sometimes even IP68 for critical items. Let's have a look at each level in relation to solar products:
IP65 – Free from dust, and resistant to water sprayed at low pressure from any angle. Suitable for the majority of inland locations that are not at risk of flooding, however, it does not meet the standards for being completely submersible.
IP66 – Free from dust, and resistant to high-powered streams of water (e.g. intense storms or high-pressure washdowns). Better suited for the majority of dry, windy and rainy climates, but still not submersible.
IP67 – Free from dust, and able to temporarily be submerged (up to 1 meter for 30 minutes). The perfect option for ground-mount solar systems in areas with seasonal flooding or where there is substantial snowmelt.
IP68 – Free from dust, and rated to be continuously submerged at a specific depth for a specific duration of time. Common applications for IP68 products include cables submerged in water (floating solar farms) or connectors buried in wet conduits.
How Are IP Ratings Tested?
To claim an IP rating, manufacturers must subject samples to rigorous laboratory tests:
Dust test (IP6X): The enclosure is placed in a vacuum‑sealed chamber filled with talcum powder (particles ≤50 μm) for 8 hours. No dust should enter.
Water tests:
For IPX5/6: A nozzle sprays water at 12.5 L/min (IPX5) or 100 L/min (IPX6) from a distance of 2.5‑3 metres for at least 3 minutes.
For IPX7: The unit is immersed in 1 metre of water for 30 minutes.
For IPX8: Deeper immersion – conditions vary, but common solar specs require 1.5 metres for 24 hours or 3 metres for 1 hour.
After testing, the device must pass an insulation resistance test and show no visible water ingress. Only then can it bear the IP rating label.
Common Misunderstandings
The IP rating is not a lifetime guarantee of waterproof seal integrity (rubber gasket hardens over time, potting replacement will be necessary as potting material cracks). In addition, reputable manufacturers conduct additional thermal cycle, humidity freeze, and colour fastness to UV light testing to verify suitability for long-term use.
IP67 is not "better" than IP66 in all ways – IP67 offers immersion protection, but IP66 withstands stronger water jets. For a module mounted on a steep roof that never sees pooling water, IP66 may be perfectly adequate and even more robust against cleaning sprays.
A complete solar panel does not have a single IP rating – The glass/backsheet laminate is considered a functional part, not an enclosure. The rating applies to junction boxes, connectors, and inverters separately.
DIY sealing can void the IP rating – Once you open a junction box or cut a connector, the original IP protection is lost. Always use factory‑made IP‑rated accessories and follow the manufacturer's assembly instructions.
Choosing the Right IP Rating for Your Solar Project
Residential rooftop: IP65 or IP66 for junction boxes; IP67 for connectors if you live in a rainy or coastal area.
Commercial flat roof: IP66 or IP67, especially if water may pool during heavy rain.
Ground‑mount farm: IP67 recommended because ground‑level modules can be submerged during flash floods.
Floating solar: IP68 mandatory for all underwater cables and connectors; junction boxes at least IP67.
Desert or dusty environment: Ensure IP6X (dust‑tight) – almost all modern components meet this. For water, IP65/66 is enough as rain is rare, but cleaning with hoses may require IP66.
